The present invention relates to a scroll compressor and, more particularly, to a scroll compressor suitably used as a compressor for air compression having an orbiting scroll with laps which are formed on one side or opposite sides of an end plate, and also to a method of manufacturing such a scroll compressor.
In conventional scroll compressors as disclosed in Japanese Patent Unexamined Publication No. 2-173472/1990, Japanese Patent Unexamined Publication No. 1-237376/1989, Japanese Patent Unexamined Publication No. 64-80785/1989 or the like, lap surfaces of a stationary scroll and an orbiting scroll are subjected to surface treatment providing a good lubrication so as to aim at reducing abrasion occurring between the scroll laps and the end plates or between the respective scroll laps, and at preventing seizure from occurring therebetween. Further, Japanese Patent Unexamined Publication No. 8-261171/1996 proposes a scroll compressor in which a stationary scroll and an orbiting scroll are both subjected to one and the same kind of surface treatment so as to aim at prolonging the service life of the scroll compressor.
In a scroll compressor in which an orbiting scroll and a stationary scroll are arranged with their laps mating with each other, revolving movements of the orbiting scroll reduces a volume of an compression working chamber, which is defined between the laps of the stationary scroll and the orbiting scroll, to compress gas therein. It is desirable in view of improvement in the performance of the scroll compressor to eliminate a gap between the laps during the operation of the scroll compressor to reduce leakage from the compression working chamber as much as possible. Accordingly, a temperature of the laps during operation is estimated to determine a gap between the laps. However, the actual scroll compressor is extremely complicated in construction, so that it is impossible to estimate a gap between the laps, which is in the order of several micron meters (.mu.m) during operation. If the gap between the laps is too narrow, such a disadvantage would occur that the laps make contact with each other during the operation, resulting in seizure which leads to stopping of the compressor.
Accordingly, in scroll compressors as disclosed in Japanese Patent Unexamined Publication No. 2-173472/1990, Japanese Patent Unexamined Publication No. 1-237376/1989, Japanese Patent Unexamined Publication No. 62-199982/1987 and Japanese Patent Unexamined Publication No. 64-80785/1989, laps are coated with a material, which provides a good lubrication, to prevent the laps from making contact with each other. However, although this coating exhibits a satisfactory function in the initial stage of the operation, it increasingly undergoes abrasion with the operating time since a substrate material for the laps is mainly composed of aluminum, and the substrate materials are eventually brought into contact with each other to possibly cause disadvantages such as seizure or the like.
Further, in a scroll compressor disclosed in Japanese Patent Unexamined Publication No. 8-261171/1996, the same coating material is used for both stationary and orbiting scrolls, which involves the possibility of causing disadvantages such as seizure and the like in the event of poor lubrication.